assistant: You're right to look for a replacement — the Zoom Fly 6 is a solid shoe, but fit issues are a real problem for marathon training, and you'll want something you trust for those long tempos and race-pace work. Before I recommend, one quick clarification: **what specifically hasn't been fitting well with the Zoom Fly 6?** Is it the forefoot width (it runs anatomically wide), the volume at the midfoot/instep, the heel lockdown, or something else? That'll help me steer you toward a shoe with a better geometry for your foot. Also, **are you looking for a dedicated tempo/speed-training shoe (lighter, snappier), or a more versatile daily trainer that can handle both easy days and tempo work?** Marathon training often benefits from a do-everything shoe you can rotate into your easy runs too — not just race-pace work. Once I know those two things, I'll have a clear pick for you.

assistant: Got it — you want a true tempo shoe, not a do-everything trainer. The Zoom Fly 6 is versatile by design, which means it's a compromise on both ends. For dedicated tempo and speed work at your mileage and pace, you want something snappier and more responsive. Here are three picks, each with a different character: **Adidas Adizero Takumi Sen v11** — *Best for pure tempo work* This is the sharpest tool in the set. At 184g, it's 60g lighter than the Zoom Fly 6, with a lower stack (32/25mm vs 40/32mm) and a fiberglass plate that's nimble without the heft of carbon. Adidas describes it as a 5K–10K racer, but it's equally at home for tempo runs and speed work. The tradeoff: it's more minimal, so it's not a daily trainer — save it for workouts and tempos. **Saucony Endorphin Speed v5** — *Best for tempo + some versatility* A nylon-plated speed trainer that splits the difference. It's cushioned enough for longer tempos (the Endorphin line is known for that), snappy enough for intervals, and light enough to feel fast. Reviewers call it well-regarded, and at $175 it's $5 cheaper than the Zoom Fly 6. You could rotate this into easy days if needed, though it's still purpose-built for work. **ASICS Megablast v1** — *Best if you want maximal cushion + tempo capability* If you find the Zoom Fly 6 a touch firm or want more protection on long tempos, the Megablast is the outlier here — maximal stack (45/37mm), no plate, but excellent for marathon-pace work and progression runs. It's heavier (221g) and more trainer than racer, so it's the pick only if you suspect you need more cushion, not less. **One more question:** Are you planning to race the marathon in a super-shoe (like a Alphafly or Adios Pro), or will you race in your tempo shoe? That changes whether you need the Takumi Sen's racing pedigree or if the Endorphin Speed's versatility is enough.

assistant: Perfect — that clarifies it. Since you're racing in a dedicated racer, your tempo shoe doesn't need to pull double duty, so the **Adidas Adizero Takumi Sen v11** is the right call here. It's the sharpest, most purpose-built option for speed work. At 184g with a 32/25mm stack and fiberglass plate, it's genuinely lightweight and snappy — Doctors of Running notes it's "much softer and bouncier" than the v10, making it more enjoyable for intervals and tempo runs than the previous version. Kofuzi calls it his perennial 5K/10K favorite, describing it as "agile and low to the ground" with "great pop." For marathon-pace tempos and speed sessions, it'll feel significantly sharper than the Zoom Fly 6's compromise ride. The tradeoff: it's not a daily trainer. At 7.0mm drop (1mm lower than the Speed v5) and minimal stack, it's purpose-built for work — save it for workouts and tempos, not easy days. **If you want a second option that's closer to a do-everything speed shoe**, the **Saucony Endorphin Speed v5** is the alternative. It's 54g heavier than the Takumi Sen and more cushioned (37/29mm stack), so it won't feel quite as sharp, but it's versatile enough to rotate into easy runs if needed. EDDBUD calls it "softer and more compressive" with an "energizing" feel across the full pace range — and at $175, it's $5 cheaper than the Zoom Fly 6 you're replacing. The **HOKA Mach X v3** is also in my data as a speed-training option with a PEBAX plate and maximal cushion, though I don't have detailed reviewer notes on it to compare directly. **One last thought on the Alphafly:** if you're still deciding on a racer, it's an excellent choice for marathon distance — well-regarded, proven, and the 40/32mm stack sits between a pure racer and a super-trainer. But that's a separate decision from your tempo shoe. Focus on nailing the Takumi Sen for your speed work first. Which direction feels right — the pure speed of the Takumi Sen, or the versatility of the Speed v5?